Juvenile myoclonic epilepsy (JME) is the most frequent cause of hereditary grand mal seizures. A JME region has been previously mapped and recently narrowed on chromosome 6p12-p11 (EJM1). Janz, J. Neurol., 176: 344-386, 1957; Delgado-Escueta, et al., Adv. Neurol., 79: 351-374, 1999; Liu, et al., Am. J. Hum. Genet., 57: 368-381, 1995; Liu, et al., Am. J. Med. Genet., 63: 438-446, 1996; et al., Am. J. Med. Genet., 133: 268-274, 2002.
Two separate loci on the short arm of chromosome 6, 6p21.3 and 6p12-p11, have been proposed as JME regions. In the 6p21.3-HLA region, two SNP variants in BRD2 were in linkage disequilibrium with JME although no causative coding mutations were found. In contrast, JME families from Belize, Los Angeles, and Mexico, showed significantly high lod scores at the 6p12-p11 locus but exclusionary lod scores at 6p21.3. Recently, an independent study of Dutch JME families confirmed 6p12-p11 as a susceptibility locus for JME. Sander, et al., Neurology, 49: 842-847, 1997; Greenberg, et al., Am. J. Hum. Genet., 66: 508-516, 2000; Pal, et al., Am. J. Hum. Genet., 73: 261-270, 2003; Liu, et al., Am. J. Hum. Genet., 57: 368-381, 1995; Liu, et al., Am. J. Med. Genet., 63: 438-446, 1996; Bai, et al., Am. J. Med. Genet., 133: 268-274, 2002; Pinto, et al., Epilepsia, 45: 211-217, 2004.